Wrong Name
by Mae Snapdragon
Summary: The closet was dark and he could feel her breath against his ear and she was calling him Truman. Something was very, very wrong here.


**I bring you Dasey, again. And there is lime. And angst. I apologize for any typos.  
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**I do not own Life With Derek. If I did, there would be a third movie called "Sex With Derek", and would feature Casey as the one sexing Derek. At university.**

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><p>Derek stumbled into the bathroom, his hand slapping hard against the wall above the cracked sink. He could hear the party raging just outside the door, bass thumping through the walls and shaking his rib cage. He could barely breathe. His hands were shaking; he could still feel the touch of silky, phantom hair wrapped around his fingers. He could hear her voice, gasping, seductive—and saying someone else's name.<p>

He felt the bile rush up his throat and he doubled over the toilet bowl, emptying his stomach. He didn't know what to be feeling: nausea churned in his gut, but at the same time, the afterglow was still thrumming through him, little streaks of pleasure echoing across his body.

His belt buckle was undone, and it clanged against the edge of the toilet as he sunk to his knees. He glanced down at the front of his pants, but there was no stains there to show what had just happened. Well, of course there wouldn't be.

She had swallowed.

He lurched forward and threw up again.

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><p>This was definitely "the" party of the year.<p>

Derek pushed his way through the crowd, nodding his head and flashing smirks at the people who tried to flag him down. No, he couldn't stop for long: he was Derek Venturi, and he had to circulate so he could spread his awesomeness to the entire party. Had to share the goods.

He spotted a monogrammed glove waving through the air and he changed direction, swerving over to the edge of the room.

"Ralphie!" he exclaimed, only distantly recognizing his friend in the dim light. Ralph was wearing a stupid look on his face and those hideous vinyl pants. Any other time, Derek would've given him grief for that, but hey, when the man was throwing the best party ever, Derek could let this opportunity for ridicule slide, just this once.

"Derek!" Ralph said back enthusiastically. A goofy grin stretched across his face, and Derek abruptly realized that his eyes were swimming, as though struggling to focus on his face. "Maaaaannn, how's it goooinng?"

"Whoa," Derek laughed, waving a hand in front of his face. "You are smashed."

"As I shouulld bee!" Ralph slurred. "Why areeent you?"

"I like to remember things in the morning. Plus, I gotta drive home," Derek replied, leaning back against the wall. It was getting a little too crowded around him for his liking—he'd leave to get some air in a second. Out of the corner of his eye, he saw a flash of brown hair. His head whipped around, but it was merely some generic party chick, not the girl he'd thought it was. "Hey, don't suppose you know if my lame stepsister is here? Knowing her, she probably hasn't touched anything that even looks like alcohol."

He was only asking because he'd seen Truman hovering around somewhere just a minute ago. He'd been talking to a group of girls, but Derek was pretty certain that Klutzilla was probably here too. Likely with Emily in tow. He was keen on avoiding Emily: he'd broken up with her two weeks ago, and he had a sinking feeling that she might cry if she saw him.

"What, Cay-shee?" Ralph said slowly. "Oooh, no, I saw her, and she looked prreeety out of it." He giggled disturbingly. "And thatsh mee talkin."

Derek raised an eyebrow. Casey, drinking? Sure, she'd been breaking more rules since she'd started going out with Truman (which irritated him for some reason), but drinking didn't seem like her thing at all.

He sucked in a breath and almost choked. Someone nearby was smoking, and it smelled awful.

"Whatever," he said, clapping Ralph on the shoulder. "I'll see you later."

He weaved through the crowd, contemplating where he could stop to get a moment of peace. Being the coolest guy in school was awesome, but even he needed a break.

Outside? Uh, no. There was a group of kids getting high there.

Upstairs? Definitely not. There were a bunch of couples getting _off_ there.

Bathroom? Kinda gross looking place, honestly.

Closet? Perfect.

Derek shut the door behind him and slumped back against the coats, closing his eyes in the darkness. His hands flattened against the coolness of the wall behind him, and he breathed out slowly. A minute of relaxation, and then he would get back out there, eat some food, find a chick, and make out with her. Good plan. There was that blond chick who had been eying him all—

The closet door swung open and a body lurched inside, colliding with him, hard. Automatically, his hands came up around their waist to steady them—his mind registering as he did so that, oh yes, this was definitely a girl—and the door slammed shut behind the new arrival, a cluster of girlish giggles fading away from outside the closet.

The girl lifted her face from his chest, but it was pitch black, hiding her features from him.

"Ooooh," she said slowly, hiccuping slightly. "You're early."

That voice was...familiar. It was so familiar that it drew chills down his spine, but it couldn't be who it sounded like, because that voice did not make any sense in this context.

"Did you get a little shorter?" the girl mused quietly, her breath puffing out against his cheek. "Oh well."

And then any thoughts on her identity were erased because she was kissing him.

Derek had about one second of shock while those warm lips pressed against his before he was automatically responding, backing her into the doorway and sliding his hands into her hair, tipping her head back for a better angle. He could taste the bitter kick of alcohol on her lips. She arched into him, her hands fisting in his shirt and yanking him to her. His mouth was insistent on hers, but she gave it back just as much, parting her lips and letting his tongue probe into her mouth. They fumbled around in the darkness, bumping against coats and knocking their hands off of things as they tried to pull each other closer.

For the first time, Derek felt clumsy. Usually he was the one who made the girl go crazy, while he kept his head and got what he wanted. But now his breath was rasping in the silence and his fingers seemed to have forgotten their learned ways of seduction. This girl—that voice had been familiar, but no, it couldn't, it _couldn't_ be—had a heat that seemed perfectly attuned to him, perfectly attuned to get under his skin and turn him inside out.

Distantly, he heard someone knocking on the door, but he reached over, fumbling with the doorknob until he found the lock and clicked it shut. He turned his attention back to the girl, but already she had taken advantage of his distraction and was planting kisses along the side of his jaw. He felt her teeth tug ever so lightly on his earlobe and he bit down on his lip, hissing.

She pulled away, pushing him against the wall before stepping up and rolling her body against his again. He felt her lips brush his throat before he heard her whisper.

"Like that, Truman?"

His racing heart abruptly stopped beating.

Oh god.

He knew who this was.

He'd probably known since the second that she had landed on top of him. He just hadn't wanted to believe it.

And she was drunk and she thought he was Truman—for some fucked up reason—and he needed to get out of here—

"Ca—"

She clapped her hand over his mouth.

"Don't say anything," she said huskily. Ralph had been right: she was drunk. He could hear it in the deliberate way she spoke every word, like she was trying not to slur. "You said that I wasn't exciting enough and that I move too slow? Well, try this."

Her free hand snaked out and traced along the edge of his hipbone, underneath his shirt, teasing along the top of his jeans. His skin recoiled violently at her touch, desperately wanting more of it. His hands were rigid at her waist, unable to move at all. He should be getting out of here because this was so wrong and this was so amazing and she thought he was _Truman__—_and yet he could feel himself growing hard, straining against his jeans.

She slid her hand into his pants and under his boxers in one smooth move. Her fingers grazed clumsily against his flesh and he jerked, a strangled sound leaking out of his mouth. His head was filled with static, and he barely registered that she was sinking to her knees, her hands tugging at his zipper.

Nonononononononononono this could not be happening, _stepsister,_** stepsister,** stop wanting it, stop touching—!

And suddenly her mouth was on him.

Derek almost collapsed, losing all control over his legs. All she had done was to lick him, her tongue swirling briefly around the tip of his dick, and he had to resort to slamming his hands against the walls to hold himself up. She seemed to take this as encouragement, because she proceeded to do it again, this time one of her hands coming up to curl around the base of his erection, holding him in place for her.

She glanced up, and he caught the tiny glint of her eyes peering through the darkness as she drew her tongue in a slow, wet path from base to tip. He gritted his teeth, trying not to make a sound. He was not allowed to enjoy this because he hated her, righ—

"Oh, fuck," he hissed. His eyes squeezed shut, his head falling back against the wall with a loud thud. He didn't need sight to feel her lips sliding over him, to feel his cock sinking inch by inch into her mouth. He was seeing colours he hadn't even known existed. It felt _so_ _fucking __good._ And yet this was wrong, wrong, absolutely wrong—

She starting bobbing her head up and down, and his hands disobeyed him, reaching out and tangling in her hair. It was obvious that she had never done this before, but she was sucking and licking with an enthusiasm that canceled out any of her inexperience. She glanced up again at him, and he stared back, suddenly terrified that she would see through the intoxication and the darkness and recognize him, realize that it wasn't her boyfriend she was doing this to, but _Derek,_and that she would stop. The voice in his head telling him that his stepsister should not have his dick in her mouth was dying, drowned out by the sensation of her tongue rubbing against him. This was wrong, but if she stopped now he thought he might die.

He could feel his gut starting to clench, and maybe she could sense it too, because she picked up her pace, humming something that vibrated up through his entire body. It took everything in him not to just thrust into her mouth, to push her head forward so he could slide down into her throat. His hands were shaking, twining in the strands of hair at the nape of her neck. He knew he should warn her, should say something so that she could back away and let him finish on his own, but he couldn't seem to get his voice to work.

And although it was way too dark for him to see any more then glimpses of her form in front of him, an image suddenly shot to the front of his mind: not of a closet, but of him sitting on his bed at home, with her kneeling between his legs, her hands in his pants, gazing up at him with those huge blue eyes.

His body stiffened and it was too late to stop it now.

His found his voice just as he came.

"Casey!"

He didn't know how long it was before he floated back down to earth, but slowly the ringing in his ears calmed down. He realized that he somehow had slid down the wall until he was sitting on the ground. His legs probably had given out on him. He was breathing hard, and he could see her still sitting in between his knees. She reached up and wiped her mouth with the back of her hand, and Derek suddenly realized that she had swallowed it.

Fuck.

For the first time ever, he had lost all control with a girl. She had literally blown his mind.

"Did...that feel good?" she said abruptly, tripping over her own words. "Truman?"

The glow disappeared faster than he thought possible as the reality of what had just happened shot through his head.

Casey, his _stepsister_, had just given him head, because she was drunk and thought that he was Truman, her boyfriend.

Why was it that the thing that hurt the most about that sentence was that she had been planning on giving _Truman _a blowjob?

She was still staring at him, waiting for an answer, but he couldn't do this. He couldn't talk to her and pretend to be someone else. He couldn't talk to her at all. He felt sick to his stomach, worse than anything he had ever felt before.

He climbed to his feet—damn it, his legs were still unsteady—and lurched over to the door. He heard her drunkenly call after him (using the **wrong** name), but he wrenched the door open and plunged out of the closet, staggering across the hall until he reached the bathroom.

_That could not have just happened._

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><p>He had to drive her home.<p>

Apparently Emily had driven them there, but she had been concerned about Casey when she found her huddled in the closet, crying, and so she had told Derek to take her home early. Derek had only agreed to do so because Emily was a weepy drunk, and he wanted to get away before she started rehashing their relationship.

It was impossible to describe how awful it was in that car, trying to ignore the girl slumped in the seat next to him.

It was worthless to try and explain how horrible it felt to have to pick her up and carry her into her room and drop her on her bed.

It didn't mean anything, right? I mean, he was a guy. Of course he was going to get off if a girl was sucking his cock. Who it was didn't matter, right?

But every single time he closed his eyes, he saw her face hovering there. And he could hear it, hear her panting and pleading. He could hear her using that crazy, whispery voice, except in his head, she wasn't thinking of Truman. She was saying _his _name.

"Derek..."

He was so screwed.

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><p>The memories didn't start coming back until she had finished all of her puking.<p>

Casey slumped over, her cheek pressed against the cold ceramic of the toilet bowl as she breathed slowly, trying to ignore the pounding of her head. She had never, ever gotten drunk like that. It was just stupid!

It had been because of Truman. They had been rocky lately. He had told her that she was going too slow, that she was boring. She'd been depressed, and she had just started drinking. It had felt nice to loosen up like that...

Distant flashes of recollection were sinking into her head. She had gotten the idea to show Truman that he was wrong. She had told Emily to tell him to meet her in the closet...

Images spun before her eyes, glimpses of memory.

Her back pressed up against a door, someone's body flattened against hers...lips on hers, different—better—than any she had ever experienced before...a cold floor underneath her knees...fingers threading through her hair...something thick and hot in her mouth, throbbing...a face, shadowed in darkness, just the tiniest hint of reddish brown hair splaying across his forehead...a voice, a familiar, familiar voice saying her name—

Her eyes shot open. She knew that voice. She knew that hair. She knew those hands.

A picture flashed in her mind unbidden: one where they weren't in the closet, but were in his room, her between his legs, able to see perfectly what his face looked like as he came.

Her hand flew to her mouth. She felt like she was choking on the air, unable to take in anything.

She had...she had...with _him_...

That was impossible. That was disgusting. That could **not have happened. **Even she couldn't have made that huge of a blunder.

She could feel the phantom heat of his hand in her hair, could feel her palms aching from how she had touched him. Her throat burned at the memory of how she had swallowed, and her tongue felt sore.

But most of all, her head was ringing with his voice, hoarse and low as he went over the edge, crying out _her _name.

No.

No.

No!

She couldn't have given her _stepbrother _a blowjob.

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><p>Of course the entire family had to be in the kitchen when she went downstairs.<p>

They were all bustling around, eating breakfast and chattering away, and _he_ was standing by the fridge, clutching a mug of hot chocolate. Though she hadn't made any noise, he somehow managed to look up just as she entered, and his eyes locked on hers.

At first they were blank, revealing nothing, but she had never been good at that, and she saw the instant when he realized. When he took in her expression and knew that she _knew. _She had never seen so much panic fill someone's face before, churning over other barely concealed emotions.

She flinched when he pushed away from the refrigerator, striding around the island towards her. She was motionless. It felt like they were the only two people in the room, but their family—it felt so _wrong _to use the term "their" family, not now that she had tasted the bitterness of his cum—members were all around them and they couldn't let anything suspicious show through. So why was he fixing his eyes on her like that?

As he drew nearer, she tensed, and he noticed. The mask slammed down across his face, but even he couldn't hide the way his gaze lingered on her mouth. Casey swallowed nervously, and his eyes suddenly darkened. She could hear his breath, and she was transfixed with the sudden, horrible realization that she wished she could feel it on her skin.

"Derek—"

She broke off her own sentence as she remembered that she had called him Truman last night. She had knelt there with his hands in her hair and her mouth on him making him pant out her name, and she had called him by the _wrong_ name.

In her peripheral vision, she saw that Marti was looking at them, peering up with her big, child eyes from where she stood behind her brother. As if he could see her watching them, Derek suddenly curved his lips into an imitation of a smirk, an imitation of normality, and pushed past her, his shoulder knocking hard against hers. Casey didn't move as he walked away, staring blankly down at the kitchen tiles.

Her shoulder stung where he had hit it.

His name was still there on her tongue, seared into it like a brand.

It felt right.

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><p><strong>I went through something like seven different endings for this before I just did it this way.<strong>

**Once again, I troll you ALL by writing something that sounds like it could be the start of a multiple chapter, but instead is merely a ONE SHOT. I like one shots. **

**And so here you go: some Dasey lemony lime and angst. And confusion. And more angst.**


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